Merge pull request #40790 from DougGregor/opaque-type-local-variables

Ensure that we set opaque type substitutions on local variables.

Author: DougGregor

lib/Sema/CSApply.cpp

@@ -8420,6 +8420,30 @@ static Optional<SolutionApplicationTarget> applySolutionToInitialization(
         cs, resultTarget.getAsExpr(), resultTarget.getDeclContext()));
   }
 
+  // If this property has an opaque result type, set the underlying type
+  // substitutions based on the initializer.
+  if (auto var = resultTarget.getInitializationPattern()->getSingleVar()) {
+    SubstitutionMap substitutions;
+    if (auto opaque = var->getOpaqueResultTypeDecl()) {
+      resultTarget.getAsExpr()->forEachChildExpr([&](Expr *expr) -> Expr * {
+        if (auto coercionExpr = dyn_cast<UnderlyingToOpaqueExpr>(expr)) {
+          auto newSubstitutions =
+              coercionExpr->substitutions.mapReplacementTypesOutOfContext();
+          if (substitutions.empty()) {
+            substitutions = newSubstitutions;
+          } else {
+            assert(substitutions.getCanonical() ==
+                       newSubstitutions.getCanonical());
+          }
+        }
+        return expr;
+      });
+
+      opaque->setUnderlyingTypeSubstitutions(substitutions);
+    }
+  }
+
+
   return resultTarget;
 }
 

lib/Sema/TypeCheckConstraints.cpp

@@ -538,29 +538,6 @@ bool TypeChecker::typeCheckPatternBinding(PatternBindingDecl *PBD,
   PBD->setPattern(patternNumber, pattern, initContext);
   PBD->setInit(patternNumber, init);
 
-  // Bind a property with an opaque return type to the underlying type
-  // given by the initializer.
-  if (auto var = pattern->getSingleVar()) {
-    SubstitutionMap substitutions;
-    if (auto opaque = var->getOpaqueResultTypeDecl()) {
-      init->forEachChildExpr([&](Expr *expr) -> Expr * {
-        if (auto coercionExpr = dyn_cast<UnderlyingToOpaqueExpr>(expr)) {
-          auto newSubstitutions =
-              coercionExpr->substitutions.mapReplacementTypesOutOfContext();
-          if (substitutions.empty()) {
-            substitutions = newSubstitutions;
-          } else {
-            assert(substitutions.getCanonical() ==
-                       newSubstitutions.getCanonical());
-          }
-        }
-        return expr;
-      });
-
-      opaque->setUnderlyingTypeSubstitutions(substitutions);
-    }
-  }
-
   if (hadError)
     PBD->setInvalid();
 

test/IRGen/opaque_result_type.swift

@@ -253,3 +253,25 @@ public enum EnumWithTupleWithOpaqueField {
   case a(Int)
   case b((OpaqueProps, String))
 }
+
+// rdar://86800325 - Make sure we don't crash on result builders.
+@resultBuilder
+struct Builder {
+  static func buildBlock(_: Any...) -> Int { 5 }
+}
+
+protocol P2 {
+  associatedtype A: P2
+
+  @Builder var builder: A { get }
+}
+
+extension Int: P2 {
+  var builder: some P2 { 5 }
+}
+
+struct UseBuilder: P2 {
+  var builder: some P2 {
+    let extractedExpr: some P2 = 5
+  }
+}